Many types of vehicles utilize two or more protruding surfaces to affect the fluid flow around the vehicle, thereby facilitating control of its flight path. Exemplary types of such vehicles include aircraft, airships, unmanned aerial vehicles, and various types of ordnance, e.g., missiles, rockets, guided projectiles, bombs, torpedoes and the like.
For example, missiles generally have a cylindrical body, with at least two aerodynamic surfaces or fins that extend outwardly from the sides of the missile body (vehicle housing) to affect the aerodynamic characteristics of the missile in flight. The fins typically have an airfoil shape that is oriented edge-on or slightly inclined relative to the airflow when the missile is flying in a straight line. These fins may be, for example, static (fixed) or dynamic (selectively movable, i.e., controllable). Fixed fins generally are used to stabilize the missile during flight and do not move once fully deployed. Controllable fins (control fins) are used to control or steer the missile by selectively varying the attitude of the fins relative to the airflow under the direction of the missile's control system.
In many cases, the fins are stowed in a position adjacent to the outside surface or within the missile body during storage and mounting on a vehicle prior to use. In some cases, the missile is stored in a tube, a canister or other protective casing, and the protective casing also may serve as a launch tube. The fins are stowed in such a manner as to permit more missiles to be stored and/or transported in a limited space. Stowing fins in such a manner also reduces the likelihood of damage to the fins during storage and handling. Additionally, such stowing maximizes subsystem packaging volume inside the vehicle housing for various components, e.g., electronic components, propulsion systems, warheads and the like.
The fins are deployed from the stowed position shortly after deployment of the missile, or during the launch phase of the missile. Various relatively complex deployment systems have been developed to permit the fins to be stowed, deployed and locked into place. Control fins may further be moved (usually only rotated) by an actuator system once the control fins are deployed.
In some cases, the fins are stowed by folding the fins like jack knifes or sling foils into the body of the vehicle through longitudinal slots in the vehicle's housing. Complicated retention features and housings are provided to retain the fins in the vehicle housing until the vehicle clears the weapon system, e.g., a bomb bay, a launch rail, a bore of a weapon system, e.g., a cannon, a gun, a howitzer, a mortar tube, a canister or the like. For example, covers are employed to seal the longitudinal slots and retain the fins until needed in flight. In some cases, multiple mechanisms are used, for example, a cover deployment system is provided to effectively discard the covers and a fin deployment system is provided to deploy the fins in flight.
Many fin deployment systems require the fins to deploy about more than one axis. That is, fin deployment systems require a fin to pivot or rotate about a first axis and then to pivot or rotate about a second axis in order to transition from a stowed configuration to a deployed configuration. In some cases, the fins transition to an intermediate configuration before transitioning to a final deployed configuration.
The systems presently used to retain, deploy, lock into place and control (if applicable) the fins tend to be relatively heavy, complex and expensive to design, build and maintain. Moreover, some systems occupy a relatively large volume within the missile, a significant disadvantage because of the limited space within the missile.